Apparatus for making underground passages

ABSTRACT

An apparatus for forcing tubular elements through soil so as to make underground passages. Hydraulic jacks are mounted in a cylindrical casing having open ends, for reciprocation axially of the casing. At least one elongated tubular element is provided which is to be axially forced into the soil by the jacks and which has a circumferentially complete annular cross section. A plurality of pressure-transmitting members are provided which are to be interposed between a trailing end of the tubular element and the hydraulic jacks. These pressure-transmitting members each have a circumferentially complete annular cross section corresponding to that of the tubular element and are composed essentially of high-strength reinforced centrifugal concrete provided with annular metallic reinforcing rings embedded at opposite axial ends of the respective pressure-transmitting member.

Weiss et a1.

[54] APPARATUS FOR MAKING UNDERGROUND PASSAGES [72] inventors: Bruno Weiss, Kolbergerstrasse 11, 4021 Metzkausen; Richard Weiss, Spichernstrasse 52, 41 Duisburg, both of Germany [22] Filed: June 29, 1970 [21] Appl. No.: 50,729

[30] Foreign Application Priority Data June 30, 1969 Germany ..P 19 33 066.6

[52] U.S.Cl ..6l/42,61/63 [51] Int.Cl ..E0lg 3/00 [58] Field oiSearch ..6l/42,43,45,84, 85,63

[56] References Cited UNITED STATES PATENTS 1,948,707 2/1934 Gilman ..61/85 1,948,733 2/1934 Robertson ....61/84 2,325,565 7/1943 Williams ....6l/42 2,967,401 1/1961 Washabaugh.. .....6l/84 Cunningham ..61/42 Levy ..61/85 Primary Examiner-Dennis L. Taylor Attorney-Michael S. Striker [5 7] ABSTRACT An apparatus for forcing tubular elements through soil so as to make underground passages. Hydraulic jacks are mounted in a cylindrical casing having open ends, for reciprocation axially of the casing. At least one elongated tubular element is provided which is to be axially forced into the soil by the jacks and which has a circumferentially complete annular cross section. A plurality of pressure-transmitting members are provided which are to be interposed between a trailing end of the tubular element and the hydraulic jacks. These pressure-transmitting members each have a circumferentially complete annular cross section corresponding to that of the tubular element and are composed essentially of high-strength reinforced centrifugal concrete provided with annular metallic reinforcing rings embedded at opposite axial ends of the respective pressure-transmitting member.

11 Claims, 1 Drawing Figure I PATENTEDHms I972 S mw wa R mmu w Mc RM APPARATUS FOR MAKING UNDERGROUND PASSAGES BACKGROUND OF THE INVENTION The present invention relates generally to an apparatus for making underground passages, and more particularly to an apparatus for pressing or forcing tubular members into the soil below ground.

lt is known to make underground passages, where the soil is loose enough and where geological conditions permit, by forcing tubular elements into the soil in axial alignment with one another until the desired passage length has been reached. This approach is used for making underground liquid conduits, underground passages for wires, cables and the like, and generally underground passages for any desired purpose where this approach is feasible. For this purpose a shaft is driven from the ground level to the desired depth and an arrangement utilizing hydraulic jacks or piston and cylinder arrangements is mounted at the desired depth. From this shaft the tubular elements are then pressed into the circumferential wall of the shaft in the direction in which the conduit or passage is intended to lead. Of course, there is a limit to the total length of a passage which can be produced by axially aligning sections of tubular elements and forcing them through the soil, this limit depending upon the force which can be exerted with the hydraulic jacks and upon the resistance of whatever support upon which the hydraulic jacks must bear. Therefore, if this limit is exceeded another shaft is driven into the ground from ground level to the desired depth at a distance from the first shaft which corresponds to the maximum length to which the tubular elements can be driven through the soil by the hydraulic jacks in the first shaft, and of course the second shaft is so oriented as to intersect the passage being produced by driving the tubular elements through the soil from the first shaft. The underground passage is then continued from this second shaft and in this manner underground passages of desired length can be produced. The shafts may conventionally be spaced between substantially 50 and 200 meters from one another and serve after completion of the passage as manholes through which personnel and equipment may enter and leave the passage.

According to one known approach of making passages in this manner the shaft may have a polygonal or circular cross section and is driven to the desired depth either by using largediameter tubular elements similar to or identical with those which subsequently are to be driven into the soil below ground for making the passage, or by using specially produced and configurated annular elements, These are placed vertically on the ground with the lower end of the lowest annular element being closed, and thereupon soil is removed from beneath until the lowest element descends into and is embedded in the ground. Now another element is placed atop the lowest element and more ground is removed until it also becomes embedded. This is continued until the shaft reaches the desired depth. The annular or tubular elements of course prevent the collapse of the walls of the thus-produced shaft. When the desired depth is reached, the sole thereof is cemented or otherwise prepared, and in the circumferential shaft wall so called concrete protective elements of tubular character are pressed into the soil at diametrally opposite sides of the shaft, with the elements being axially aligned and with their axes extending in the direction and, if necessary, at the inclination which the passage to be produced is to have. The length of these protective tubular elements is usually about 1.5 to 2 meters and their cross section is such that the tubular elements which are to form the underground passage can be passed through them. The tubular protective elements may remain in place even after the passage is completed and in effect constitute a connection at the ends of the passage where the latter joins with the shaft. Of course, the shaft wall is previously provided or is subsequently to completion of the shaft provided with openings through which these tubular elements can be pushed into the soil.

Once the shaft has been sunk and prepared in this manner, the actual production of the underground passage can begin. According to one approach this is done by utilizing tubular elements having a length of approximately 1.5 1.8 meters. This amounts to about half the length at which such tubular elements are ordinarily produced. Normally they have a length of between 3 meters and 3.6 meters and a nominal diameter of between cm. and 3.5 meters and consist of reinforced centrifugal concrete. However, using tubular elements having only about half the standard length has the advantage that the working and access shaft which must first be sunk need have only a smaller cross-sectional area than would otherwise be required. A pressing station is arranged in that protective tubular element which is located at the side of the shaft facing away from the direction in which the passage is to be driven. Suitable reinforcements are provided against which the hydraulic jacks of the pressing station can bear, and it will be appreciated that a plurality of such hydraulic jacks are arranged in axial parallelism with one another. Now the first tubular element is lowered from above and is provided at that one of its ends which in operation will be the leading endthat is the one that is to be driven first into the soilwith a cutting edge such as a beveled or inclined edge. It is arranged so as to extend in axial parallelism with the hydraulic jacks and to be pushed into the opposite one of the tubular protective elements. This is done and thereupon the hydraulic jacks proceed to push the first tubular element into the soil at the outer end of the protective tubular element. The operating or working stroke of the hydraulic jacks is usually approximately 55 cm. and because of this the tubular element is driven into the ground in stepwise manner by interposing pressure-transmitting members between its trailing end and the hydraulic jacks. 1f the length of the tubular element itself is between 1.5 and 1.8 meters, at least four of these pressure-transmitting members are needed and according to the prior art they are of approximately U-shaped cross-sectional configuration with the open side of the cross section facing upwardly. The purpose is to permit removal of the soil which is moved rearwardly through the respective tubular element from the leading end thereof by means of a suitable carriage capable of advancing within the tubular element. The carriage is then lifted out once it reaches the access shaft. Of course, the upper open side must then provide sufficient clearance for permitting the removal of the carriage.

A problem existing in this prior art approach is the fact that the U-shaped cross-sectional configuration of the pressuretransmitting members require that they be constructed of steel, a construction which is very expensive. In addition this great expense makes it highly uneconomical to have such pressure-transmitting members on hand for various different cross-sectional configurations of the tubular elements to be driven into the soil. Evidently, any such pressure-transmitting members which are for only infrequently required cross-sectional configurations will mean an economically indefensible tying-up of capital and it is therefore not practical to have more than one or two sets of these elements available for the most common cross-sectional configurations. On the other hand, however, this means that whenever a cross section configuration is required which is not on hand, the necessary pressure-transmitting members must be specially made and this not only makes them more expensive but also is rather timeconsuming because their manufacture is relatively complicated so that it adversely influences the time calculations required for producing the underground passage in question.

In addition the pressure-transmitting members of substantially U-shaped cross section have the significant disadvantage that they exert an evidently unevently distributed force upon the trailing end of the tubular element which is being driven into the ground-or the respectively trailing element if more than one is driven simultaneously in axial alignment of the various tubular elements-because the trailing end of the tubular element which is contacted by the pressure-transmitting members is circumferentially complete whereas the pressuretransmitting members themselves are circumferentially incomplete. Evidently, the distribution of force is uneven and therefore can lead to damage of the trailing end of the respective tubular element in contact with the leading pressuretransmitting member.

A further and different prior art approach mounts the entire pressing station with the hydraulic jacks for movement along with the tubular elements as the latter are being driven into the soil. In this construction suitable guide means must be provided and the entire large rather complicated and very expensive pressing station as well as the trailing end of the tubular element (or the trailing tubular element of a set of axial aligned tubular elements) must be mounted on rollers which move on guide rails which are provided on the sole of the working or access shaft. This is evidently not only expensive but alsodisadvantageous, particularly because the pressing station itself must be on the order of two meters long or more, and because the tubular elements used in this approach are usually between 3 and 3.6 meters long. This means that the cross section of the access or working shaft must be very large because it must be able to accommodate the length of the pressing station as well as of one tubular element. There must be further additional space for the personnel and tools and the entire available length must be on the order of between substantially 7 and 10 meters which is very disadvantageous.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome the aforementioned disadvantages.

More particularly it is an object of the present invention to provide an improved apparatus for forming underground passages which is not possessed of the aforementioned difficulties.

A concomitant object of the present invention is to provide such an improved apparatus which is very simple and rather inexpensive in its construction and operation.

Still a further object of the invention is to provide such an apparatus which can be readily adapted to various different local circumstances and conditions.

An additional object of the invention is to provide such an apparatus which is reliable and simple in its operation.

Still a further object of the invention is to provide such an apparatus which is of relatively small dimensions and whose inexpensive and simple construction and operation permit a significant reduction in the expense of producing underground passages by driving tubular elements into the soil.

in pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in an apparatus for forcing tubular elements through soil so as to make underground passages. This apparatus comprises, briefly stated in accordance with one embodiment, pressing means adapted to be arranged below ground level and including advancing means reciprocable towards and away from an exposed soil surface. At least one elongated tubular element is provided which is to be axially forced into the soil from said exposed soil surface, and which has a first predetermined circumferentially complete annular cross section. A plurality of pressure-transmitting members is adapted to be interposed between a trailing end of the tubular element and the advancing means, and these pressure-transmitting members each have a second circumferentially complete annular cross section corresponding to the first cross section and are composed essentially of high-strength reinforced centrifugal concrete having annular metallic reinforcing portions embedded at opposite axial ends.

The annular reinforcing portions are preferably of steel and preferably embedded during centrifuging of the concrete. The latter preferably incorporates synthetic resin material and must have a compression strength of at least 1,000 kg./cm.

By utilizing such concrete and such reinforcements for the pressure-transmitting members, rather than relying on the previous steel construction, the pressure-transmitting members can be produced not only much more quickly than heretofore but also at a fraction of the previous cost. By giving them a cross section which is circumferentially complete, rather than interrupt it as in the case of the previously known U-shaped or analogous cross section, the force transmitted to the trailing end of the tubular element in contact with the respective pressure-transmitting member is evenly distributed and the danger of damage to the trailing end of the tubular element is significantly reduced or completely eliminated.

It is advantageous to provide the pressure-transmitting members in two axial lengths, firstly of a length which is slightly less than the length of the working stroke of the hydraulic jacks, and secondly of a length which is double or substantially double that of the first length. The reason for this will be readily understood when one assumes, by way of example, that the hydraulic jacks have a working-stroke length of approximately 55 cm. and the tubular elements to be pressed into the soil have a length of approximately 1.8 meters. Given these dimensions, it is enough to use a total of three pressuretransmitting members, namely one having a length of approximately 45 cm. and two each having a length of approximately cm. This is sufficient to drive the tubular element into the soil by the requisite distance, whereupon the pressure-transmitting members are removed and a new tubular member (if more than one is to be driven) is put in place so that its leading end abuts against the trailing end of the tubular element which has already been driven. The reduction in the expense of making the pressure-transmitting members is due to the fact that the expenses involved in making the longer pressure-transmitting members are only insignificantly higher than those involved in making the shorter one.

Instead of providing the pressure-transmitting members with an upwardly directed opening-as is the case in the prior art by giving them U-shaped cross-sectionthe present invention provides a pressing station which is so constructed that the soil to be removed can be lifted upwardly and out of the pressing station itself. This has the further advantage that it makes it possible to arrange the pressing station itself within the confines of the access shaft rather than requiring that it be accommodated in that one of the protective tubular element which is embedded in the soil at the side of the shaft opposite that where the passage is being driven.

According to a preferred embodiment of the pressing station itself, the latter is in form of a cylindrical casing provided in its circumferential wall with an opening which in operation will be upwardly directed, facing the upper open end of the shaft, with the wall being made of steel. Steel rings are mounted on the wall at the inner side thereof and are provided with a plurality of axially parallel holding arrangements for the respective hydraulic jacks. Advantageously two such steel rings are provided which are axially spaced with the holding arrangements in one ring always being axially aligned with the corresponding holding arrangement in the other ring. Thus, any desired number of hydraulic jacks requisite for a particular job can be mounted. If the pressing station is to be used in an access shaft of relatively small cross-sectional area, then it may be necessary to lift the pressing station upwardly and out of the access shaft when a new tubular element is to be lowered into the latter for driving into the soil. This is a simple matter, however, because a crane or similar lifting device must be present in any case to permit lowering of the tubular elements and this can be utilized for lifting the pressing station temporarily out of the shaft and subsequently re-introducing it.

An additional advantage of the pressing station according to the present invention is the fact that it makes it possible to drive passages in two diametrally opposite directions of a single access shaft. This is possible because utilizing the pressing station according to the present invention, the tubular element or elements already pressed in one direction into the soil can subsequently be used as a support upon which the hydraulic jacks of the pressing station bear for pressing a tubular element or tubular elements into the soil at the diametrally opposite side of the access shaft, and for this purpose it is simply necessary to turn the pressing station around through 180.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a somewhat diagrammatic fragmentary sectional elevation, with parts broken away, illustrating an apparatus according to the present invention in position for use in the ground.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the ground or soil is identified with reference numeral 5. While the upper level or surface of the ground 5 is not illustrated it will be appreciated that reference numeral 1 identifies the lower portion of an access shaft which has been driven downwardly from the upper surface through the ground 5, with the sole 2 of the access shaft 1 being concreted. A pair of concrete protective elements 4 and 4 are driven into the soil 5 at diametrally opposite locations of the shaft 1 at the desired height and axial orientation at which an underground passage 3 is to be produced. The leading ends of the tubular elements 4 and 4 are provided with beveled or otherwise suitably configurated cutting edges 4a to facilitate their pressing into the soil.

The cross-sectional configuration of the tubular protective elements 4 is such that individual tubular elements 6 can be pushed through them without difficulty so as to be pressed into the soil. It is these tubular elements 6 which form the passage 3. While the drawing does not show this, the leading end of the leading tubular end 6 has arranged in front of it in the manner already known and conventional in this field, a steel cutting ring which has the same function as the cutting edges 4a on the elements 4 and 4'.

Located in the shaft 1 is a pressing station 7 in form of a steel cylinder 8 which is mounted essentially horizontally and provided in its circumferential wall with an opening which is directed upwardly towards the upper open end of the shaft 1. In the illustrated embodiment the cylinder 8 is provided with two circumferentially extending steel rings 9 which are axially spaced from one another and each of which is provided with a plurality of openings 9a which extend in axial parallelism with one another. Each opening 9a in one ring is in axial alignment with a corresponding opening 9a in the other ring. A requisite number of standard pressing jacks, such as standard hydraulic cylinders whose construction needs no detailed description, is introduced into the respectively aligned openings 9a of these rings 9. The number of such jacks required will of course depend upon the force which they can exert as well as upon the force which is required in a given circumstance, and the jacks are identified with reference numeral 10. They may for instance have an operating or working stroke of 55 cm. or else more or less. The trailing ends, that is those which provide the support of the jacks, abut against a steel supporting ring 11 which in turn is supported against a tubular element 6 received in the tubular protective element 4, and in turn the thus received tubular element 6 abuts against the soil at the outer or remote end of the element 4'.

The rams of the jacks are identified with reference numeral l2 and in the illustrated embodiment press against a pressure-transmitting member 130 constructed in accordance with the present invention and having a circumferentially complete cross-sectional configuration corresponding to that of the tubular elements 6 which are to be pressed into the soil 5 to form the passage 3. The member 13a has a length of approximately 45 cm. Arranged subsequent to the member 13a are two similar members 13b which are, however, both of double the axial length of the member 13a, that is they each have a length of approximately cm.

The members 13a and 13b consist of centrifugal concrete including synthetic resin material and having embedded therein a double-layer spiral steel reinforcement 14; their pressure resistance is at least 1,000 kg./cm. and they each are provided at their opposite axial ends with an embedded steel pressure ring 15. The axial strength of the ring 15 is such, for instance approximately 50 mm., that the pressure of the rams 12 against the axial ends of the members 13 and 13b cannot cause any damage to these members.

It will be appreciated from the drawing that soil entering the leading end of the respective leading tubular member 6 which is being pressed into the soil with this arrangement, can readily be placed into a nonillustrated carriage in the interior of the tubular elements 6, and of course by means of the pressuretransmitting members 13a, 13b the entire string of axially aligned tubular elements 6 is constantly stepwise advanced by the pressing station 7. After each working stroke is completed, either a short pressure-transmitting member 13a or a long member 13b is inserted between the trailing end of the respective member 13a or 13b which precedes it and the temporarily withdrawn rams l2, and the rams are then advanced again. After all three of the members 13a, 13b have been pressed forwardly in this manner and in turn have advanced the tubular elements 6 into the soil by a distance corresponding to the total combined axial length of the members 13a and 13b, they are withdrawn and a new tubular element 6 is inserted. This is done in a simple manner by lifting the members 1311 and 13b as well as the pressing station 7 upwardly out of the shaft 1 with a crane or the like, whereupon a new tubular element 6 is lowered into the shaft prior to reintroduction of the station 7 and the members 13a, 13b. The preceding steps are then repeated.

The soil-filled carriage or carriages roll inside the tubular elements'6 on a sheet metal or other temporary flooring supported by the rings 9, and are moved rearwardly until they enter the cylinder 8 and are aligned with the opening 16 in the circumferential wall of the latter, whereupon they are lifted out of the opening 16 and the shaft 1 by suitable lifting device at or near ground level.

As pointed out before, the station 7 can be turned through and tubular elements 6 can then be pressed into the soil 5 in axial alignment with the ones which have just been introduced, but in opposite axial direction. The operation is the same as already described with the already introduced string of tubular elements 6 now serving as an abutment for the hydraulic jacks.

The invention resolves all of the problems which have been found disadvantageous in the prior art, and does so in a simple, inexpensiveand highly reliable manner. The construction according to the present invention requires little space and can be adapted to various different requirements in a simple, speedy and efficient manner.

It will be understood that each of the elements described above, or two or more together, may also find a useful application other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus for making underground passages, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Apparatus for making underground passages, comprising conduit means adapted to be driven into the soil so as to form an access shaft therein, said conduit means having a circumferential wall provided with a pair of diametrally opposite apertures of predetermined diameter; pressing means including a pressing station located in its entirety in said access shaft within the confines of said circumferential wall and underground at the level of said apertures, said pressing means comprising advancing means reciprocable towards and away from an underground soil surface exposed through one of said apertures; at least one elongated tubular element which is to be forced axially into the soil from said exposed soil surface, and having a circumferentially complete annular cross section and a smaller second diameter; and a plurality of pressuretransmitting members adapted to be interposed between a trailing end of said tubular element and said advancing means, said pressure-transmitting members each having a second circumferentially complete annular cross section corresponding to that of said tubular element, a third diameter corresponding to said second diameter, and being composed essentially of high-strength reinforced centrifugal concrete having annular metallic reinforcing portions embedded at opposite axial ends.

2. Apparatus as defined in claim 6, said pressing station comprising a cylindrical housing adapted to be normally positioned in at least substantially horizontal orientation and having in its circumferential wall a normally upwardly directed inlet and outlet opening communicating and substantially axially parallel to said conduit means.

3. Apparatus as defined in claim 1, wherein said reinforcing portions are centrifugally embedded.

4. Apparatus as defined in claim 1, wherein said centrifugal concrete has a resistance to compression of at least 1,000 kg./cm.

5. Apparatus as defined in claim 3, wherein said centrifugal concrete consists in part of synthetic resin-material.

6. Apparatus as defined in claim 1, wherein said advancing means has a working stroke of predetennined length; said pressure-transmitting members comprising a first member having a first axial length slightly smaller than said predetermined length, and a second member having a second axial length at least substantially equal to twice said first axial length.

7. Apparatus as defined in claim 1, said advancing means comprising fluid-operated cylinder and piston means.

8. Apparatus as defined in claim 2, said housing consisting essentially of steel.

9. Apparatus as defined in claim 2, said pressing means further comprising a plurality of axially spaced annular guide elements located at an inner side of said circumferential wall and extending circumferentially of said cylindrical housing, said guide elements being arranged with a plurality of axially oriented mounts for said cylinder and piston means with the mounts in the respective guide elements being aligned axially of said housing.

10. Apparatus as defined in claim 9, said cylinder and piston means comprising a plurality of cylinder and piston units each lodged in axially aligned mounts of the respective guide elements.

11. Apparatus as defined in claim 9, wherein said guide elements are steel rings. 

1. Apparatus for making underground passages, comprising conduit means adapted to be driven into the soil so as to form an access shaft therein, said conduit means having a circumferential wall provided with a pair of diametrally opposite apertures of predetermined diameter; pressing means including a pressing station located in its entirety in said access shaft within the confines of said circumferential wall and underground at the level of said apertures, said pressing means comprising advancing means reciprocable towards and away from an underground soil surface exposed through one of said apertures; at least one elongated tubular element which is to be forced axially into the soil from said exposed soil surface, and having a circumferentially complete annular cross section and a smaller second diameter; and a plurality of pressure-tRansmitting members adapted to be interposed between a trailing end of said tubular element and said advancing means, said pressure-transmitting members each having a second circumferentially complete annular cross section corresponding to that of said tubular element, a third diameter corresponding to said second diameter, and being composed essentially of high-strength reinforced centrifugal concrete having annular metallic reinforcing portions embedded at opposite axial ends.
 2. Apparatus as defined in claim 6, said pressing station comprising a cylindrical housing adapted to be normally positioned in at least substantially horizontal orientation and having in its circumferential wall a normally upwardly directed inlet and outlet opening communicating and substantially axially parallel to said conduit means.
 3. Apparatus as defined in claim 1, wherein said reinforcing portions are centrifugally embedded.
 4. Apparatus as defined in claim 1, wherein said centrifugal concrete has a resistance to compression of at least 1,000 kg./cm.2.
 5. Apparatus as defined in claim 3, wherein said centrifugal concrete consists in part of synthetic resin-material.
 6. Apparatus as defined in claim 1, wherein said advancing means has a working stroke of predetermined length; said pressure-transmitting members comprising a first member having a first axial length slightly smaller than said predetermined length, and a second member having a second axial length at least substantially equal to twice said first axial length.
 7. Apparatus as defined in claim 1, said advancing means comprising fluid-operated cylinder and piston means.
 8. Apparatus as defined in claim 2, said housing consisting essentially of steel.
 9. Apparatus as defined in claim 2, said pressing means further comprising a plurality of axially spaced annular guide elements located at an inner side of said circumferential wall and extending circumferentially of said cylindrical housing, said guide elements being arranged with a plurality of axially oriented mounts for said cylinder and piston means with the mounts in the respective guide elements being aligned axially of said housing.
 10. Apparatus as defined in claim 9, said cylinder and piston means comprising a plurality of cylinder and piston units each lodged in axially aligned mounts of the respective guide elements.
 11. Apparatus as defined in claim 9, wherein said guide elements are steel rings. 